【摘要】 <正> 程序升温脱附(TPD)技术已广泛应用于催化和表面化学研究.峰温T_m是一个重要的实测值,常被用于计算脱附活化能E_d和指前因子A.Brenner等指出,T_m校正与否对E_J值的影响甚至会产生成倍的误差,并认为校正值ΔT_m=τβ中的滞后时间为一常更多还原

【Abstract】 It is of great significance to get a correct peak temperature Tm, because the activation energy of desorption Ed is related to Tm, and ΔTm = τβ, where r is the time lag/lead (see Eq. (2) and Fig. 2) and β is the heating rate.Furnacing a tube, which is made of stainless steel, silica glass, or GGl7 glass, we get linear temperature-time relationships with almost the same value of β at any point of the locations shown in Fig. 1 (see Fig. 3), but r decreases as β is increased (see Figs. 4, 5) and as a special condition τ is zero for any β (see Fig. 5). These facts show that τ cannot be used as a constant as proposed by Brenner et al. So that in order to get a correct Tm, it is necessary either to select both the most suitable positions of the thermocouple and the sample bed or to make a relationship of τ-β for the Tm correction.The Ed values obtained by the plotting method according to Eq. (3), and the consulting table method (CTM) are compared in Table 1. It shows that the influence of a definite discrepancy of Tm on the Ed varies with what theoretical method has been used, and the CTM is a better one. It originates from that the CTM, by which the Ed can be determined from a single TPD peak, takes the hologram of a spectrum, while the plotting method only fetches special values, e. g. a set of peak temperatures of TPD spectra.更多还原